جستجوی مقالات مرتبط با کلیدواژه « newsprint » در نشریات گروه « صنایع چوب و کاغذ »

One of the drawbacks of utilizing non-forest fast growing species of Poplar as raw materials to produce newsprint in Mazandran Pulp and Paper Mill is fairly low bulk and opacity of produced paper at the yield of 85% (current CMP yield of the Mill). In this research work, the effect of process parameters (cooking yield and freeness) on the optical and mechanical properties of chemi-mechanical pulp was investigated. The chemi-mechanical pulps of poplar was prepared at four various levels of cooking yield, through changing the cooking time, and their properties at different level of freeness were evaluated in comparison with the control sample of Mazandran Pulp and Paper Mill (75% hornbeam and 25% beech). Strength properties of the paper pulps stemmed from the cooking yields of 85.25% to 90.4% were higher and more favorable than the control sample. By contrast, the strength properties of the produced paper pulp from the cooking yield of 94.6% were inferior to prepared paper pulp from the control sample. According to the results, there is the possibility of significant improvement of the strength properties, opacity and bulk of the chemi-mechanical pulps of poplar trough controlling the process parameters like cooking yield and freeness to utilize it as raw material of newsprint production in Mazandran Pulp and Paper Mill.

In this study, the possibility of using ash and orange bleached CMP pulp as replace in the full or part of CMP pulp of Mazandaran Wood and Paper Industries (MWPI) for making newsprint was investigated. For this purpose, first, ash and orange CMP pulps were prepared by using cooking conditions of MWPI with 101 gr/lit Na2O at the yield 85% in 75 minutes. Then some of the CMP pulps bleached with hydrogen peroxide, then its mixed samples with 15, 30, 45 and 60 percent to CMP pulp mill (control sample). From the mixed pulps provided hand sheets with 60 gr/m2 and these optical and mechanical properties measured and the data average were analyzed and compared. The results showed that newsprint from ash CMP pulp were more suitable than CMP pulp mill in all measured properties (except brightness) and orange CMP pulp (except opacity). Following bleaching with hydrogen peroxide, the brightness, tear, burst, tensile and breaking length strengths increased and opacity decreased. The results showed that ash and orange unbleached CMP pulps are not good properties for newsprint production and these pulps have to bleach with hydrogen peroxide. In generally, the best mixed pulps were includes 45-60 percent ash and orange bleached CMP pulps with 40-55 percent MWPI CMP pulp for newsprint production.

In the present research , the effect of utilizing a mixture of Birch with Hornbeam & Beech species (in the comparison with sample CMP( 75% Hornbeam 25% Beech) , on the mechanical and optical properties of papers produced within the domain of Freeness degree (CSF) of 300 ml and 85% yield has been reviewed . The CMP was prepared in accordance with 85% yield condition , different cooking times (30-120 min) , temperature of 170°C and white liquor ratio to chips in 7 to 1 & 20% Sulfide based on chips dry weight at 4 levels of 10, 20, 30 & 100% Birch mixed with Birch and Hornbeam species. After defibration and preparation of 60gm hand sheets, the optical and mechanical properties of that were assessed. The results indicated that by increasing the percentage rate of Birch , the quality of the manufactured paper was also increased and the best strength and optical properties were related to the 30 & 100% consumption rates of Birch in mixture with Beech and Hornbeam species.

In this study, production of bleached chemical- mechanical pulp from wheat straw for newsprint papermaking was investigated. Wheat straw for pulping was obtained from Lorestan province. Wheat straw CMP pulp was prepared at 120, 140, and 160 °C temperature, 45 minute time, 10, 12, and 14% chemicals charge and 10:1 cooking liquor and straw ratio. The yield after defibration treatment varied between 56.5% and 72.5%. Two optimum pulps bleached by TCF method applying 2% and 3% NaOH, 1.5% and 2% H2O2, and 60 and 120 minutes bleaching time. One way analysis variance method showed that bleaching time had the most significant effect on optical properties of handsheet. Applying 3% (based on oven dry weight of the unbleached pulp) NaOH, 2% H2O2, and 120 min. in bleaching improved the brightness and opacity to 52.9%, and 79.5% ISO, respectively. Optimum pulp strengths including tensile, burst and tear indices were measured 43.87 Nm/g, 2.18 kPa.m2/g, and 8.46 mN.m2/g, respectively. All the strengths were higher than newsprint paper strength produced by Mazandaran wood and paper and Korean companies.

This research and aim was using Bamboo and Reed CMP pulp for newsprint production. For this purpose, some chips of bamboo stem in the west of Mazandaran were randomly chosen. Then CMP Pulps were prepared at the yield 85%in 120 minutes(Bamboo) and 31 minutes(Reed), by using cooking conditions of Wood and Paper Industries of Mazandaran 60 gr/m2 newsprint handsheets were prepared from the Bamboo and Reed CMP and Mill(MWPI) CMP pulps, first in a separate and then mixed way with 25,50,75 percents. Then the optical and mechanical properties were measured and compared according by using TAPPI Standard test methods. The results showed that the most strength of the burst, breaking length, tensile, tear strength, yellowness and opacity were in the handsheets obtained from 100% the bamboo CMP pulp and the lowest strength (except brightness) was in Reed CMP pulp. The results also pointed out that the above-mentioned all strengths (except brightness) can be improved by using 25-100% of the bamboo CMP pulp, too. The results also indicated that 25-100% of the bamboo CMP pulp and 25% of the Reed CMP pulp can use for newsprint production.